The invention relates to a system and method for automatically evacuating neon tubes and filling the tubing with a neon gas or gas mixture.
Previously, various pumping systems have been proposed for evacuating and filling neon tubes, such as used in neon signs, with neon and other gas mixtures. Typically, the neon pumping system has included a manifold, a mechanical pressure gauge having a visual display connected to the manifold, and a series of greaseless stopcock valves, which are manually operated, controlling the various flows in the manifold. The stopcock valves typically connect the neon tubes with a vacuum pump assembly, and a source of replenishment gas, such as neon or other gas mixture. Stations for filling neon tubes may be placed on opposing ends of the manifold. There is a system stopcock connected between the manifold and the vacuum pump. A diffusion pump may be connected in a by-pass line with the vacuum pump so as not to be connected in use except after the vacuum has been reduced to a certain level, and it is necessary to achieve an even higher vacuum. Alternatively, a diffusion pump may be connected in a second line, with a second vacuum pump. In use, the system stopcock is opened, and the main stopcock to the vacuum pump is opened simultaneously with turning on the pump. The system is manually operated to control the pressure in the tubes as visually determined from the gauge display, and evacuate the tubes to a desired vacuum whereupon the system stopcock to the vacuum pump is closed. During the evacuation process, an electrical potential is placed across the neon tubes to cause the tubes and gases therein to be heated. The stopcock to the vacuum pump may be opened if the pressure becomes too high in the tube during heating. When the temperature and vacuum conditions inside the tube have reached a desired level the electrical potential is removed from the tubes, and the tubes are allowed to cool. Afterwards, the stopcock to the gas source is opened to backfill the tubes with gas, or gas mixture.
One problem with the prior neon pumping systems is that the manual operation often results in the neon tubes not being filled properly. If the neon tubes are not filled properly, then their life will be reduced, and/or they may not produce the desired lighting effect during their life. The suitability of prior neon pumping systems has been limited to that of small neon shops.
It has also been proposed to manually evacuate neon tubes, and afterwards, to automatically fill the neon tube with a gas. The gas flow is automatically cut off when desired gas-filling settings are reached. The gas transfer is electronically controlled to provide consistent filling specifications each time a tube is processed. However, this does not overcome all the problems associated with manual control, nor control all of the conditions required to process neon tubes to exact specifications, particularly as would be suitable for the mass production of neon tubing and lights.
Accordingly, an object of the invention is to provide a neon evacuation and filling system and method for neon tubes which is automated so that optimal conditions are produced in a tube during evacuation and gas backfilling to provide correct color and long life for the tube and neon sign.
Another object of the invention is to provide an automated system and method for evacuating and filling neon tubes which eliminates human error and performs the steps in the evacuation and filling processes whereby the processing of large numbers of neon tubes may be had according to predetermined specifications to facilitate the mass production of high performance neon tubes.
Another object of the invention is to provide an automated system for evacuating and filling neon tubes which carries out the operational steps of evacuating and filling a tube with neon, or other gas mixture, yet is very simple and reliable to operate.
Yet another object of the invention is to provide a system for evacuating and filling neon tubes in an automated manner which is simple, reliable, and reduces the problems associated with electrical controls of such a system that employs high temperatures and electrical potentials on the tubing during operation.
Still another object of the invention is to provide a fully automated system and method for evacuating and filling neon tubes an electrical controller programmed with operational data of the automatically controls pneumatic actuator valves in response to sensed parameters to carry out evacuation and gas filling of a tube in an optimal manner.